Rotary stuffing box and seal assembly

Abstract

A rotary stuffing box assembly, particularly adapted to form a rotary shaft seal for a downhole well pump includes a housing mountable on the upper end of the well tubing or other support structure and a cover threadedly connected to the housing and forming a closed chamber in the housing for holding a quantity of seal lubricant and/or coolant fluid. A resilient rotary shaft seal element is retained in a seal holder within the housing by an axially split seal retainer which is mountable in a bore in the seal holder. The retainer and the seal holder are retained between opposed transverse faces on the cover and on the housing and the seal holder engages a retaining pin on a threaded plug which closes a fluid drain port of the housing. The seal holder and retainer are operable to undergo limited radial excursion to accommodate eccentricity or excursion of the shaft. Spare seal elements may be carried on the shaft adjacent to the cover and the shaft may have a replaceable and adjustable hard faced sleeve defining a seal element engaging surface. The seal element may be changed without disconnecting or removing a pump drive structure from the shaft or removing the stuffing box from its support structure.

What is claimed is: 
     
       1. A stuffing box and seal assembly for forming a substantially fluid-tight seal at a rotary shaft, comprising: a housing including means for connecting said housing to a support structure, said housing including a bore for receiving a rotary shaft extending therethrough, a first transverse face on said housing and a chamber defined at least in part by said housing;   a cover including a transverse wall portion and a bore extending therethrough for receiving said rotary shaft, said cover including a second transverse face adapted to be opposed to said first transverse face, said cover and said housing including cooperable means for connecting said cover to said housing;   a seal holder disposed in said chamber and including means for supporting a resilient seal element, said seal holder including a third transverse face operable to be opposed to and adjacent to said first transverse face; and   a seal retainer operable to be disposed around said rotary shaft and including opposed surfaces thereon engageable with said seal holder and said second transverse face for retaining said seal element in a working position in sealing engagement with said rotary shaft, said seal retainer including opposed parts adapted to be disposed around said rotary shaft and retained between said cover and said seal holder, said parts of said seal retainer being separable one from the other for removing said seal retainer from said rotary shaft to provide for replacing a seal element supported on said seal holder.   
     
     
       2. The stuffing box assembly set forth in claim 1 wherein: said seal element is disposed in a bore in said seal holder; and   said parts of said seal retainer are retained in an assembled position of said seal retainer by a hub portion of said seal retainer which is operable to be disposed in said bore in said seal holder.   
     
     
       3. The stuffing box assembly set forth in claim 1 including: retaining means supported on said housing and engageable with said seal holder to substantially prevent rotation of said seal holder in said chamber.   
     
     
       4. The stuffing box assembly set forth in claim 3 wherein: said retaining means comprises at least one pin extendable into a slot formed in said seal holder and said pin is connected to a plug member removably supported on said housing for closing a drain port for said chamber.   
     
     
       5. The stuffing box assembly set forth in claim 1 wherein: said seal holder includes passage means formed therein between said seal element and said chamber for conducting lubricant and/or coolant fluid from said chamber to said seal element.   
     
     
       6. The stuffing box assembly set forth in claim 1 wherein: said cover is threadedly engaged with said housing and includes a distal end portion engageable with a surface on said housing to define a limit position of said second transverse face with respect to said first transverse face which permits limited radial excursion of said seal holder and said seal retainer with respect to said housing.   
     
     
       7. The stuffing box assembly set forth in claim 6 wherein: said seal retainer includes a part engageable with said bore in said cover for limiting the radial excursion of said seal holder and said seal retainer with respect to said housing.   
     
     
       8. The stuffing box assembly set forth in claim 1 including: a passage formed in said housing and in communication with a space between said housing and said support structure for conducting pressure fluid from said space to the exterior of said housing.   
     
     
       9. The stuffing box assembly set forth in claim 1 including: seal means supported on one of said seal holder and said housing and forming a substantially fluid-tight seal between said first and third transverse faces.   
     
     
       10. The stuffing box assembly set forth in claim 9 wherein: said housing includes a circumferential groove formed in said first transverse face, and said seal means comprises a resilient seal ring disposed in said groove and engageable with said third transverse face on said seal holder.   
     
     
       11. The stuffing box assembly set forth in claim 1 wherein: said seal element is a pressure set resilient seal element engageable with said rotary shaft to substantially prevent pressure fluid from flowing from said support structure to the exterior of said stuffing box assembly.   
     
     
       12. The stuffing box assembly set forth in claim 1 including: sensing means for sensing a fluid level in said chamber.   
     
     
       13. The stuffing box assembly set forth in claim 1 including: means forming a dam supported on said shaft and disposed within a recess formed on said seal retainer to minimize flow of fluid along said shaft between said seal element and said bore in said cover.   
     
     
       14. The stuffing box assembly set forth in claim 1 wherein: said shaft includes a seal engaging sleeve supported thereon and means for adjusting the position of said sleeve with respect to said seal element to provide a substantially unworn sealing surface on said sleeve engageable with said seal element to minimize fluid leakage between said seal element and said shaft.   
     
     
       15. The stuffing box assembly set forth in claim 1 wherein: said seal retainer and said seal holder include cooperating surfaces engageable with each other to limit the working position of said seal retainer with respect to said seal holder and said seal element to retain said seal element in said seal holder without substantial forcible engagement of said seal element by said seal retainer.   
     
     
       16. The stuffing box assembly set forth in claim 1 including: at least one spare seal element stored in a non-working position on said shaft and operable, upon disconnecting said cover from said housing and movement of said seal retainer with respect to said shaft, to be moved along said shaft into a working position with respect to said seal holder.   
     
     
       17. The stuffing box assembly set forth in claim 16 wherein: said seal retainer includes an annular cavity formed therein for storing at least one spare seal element.   
     
     
       18. The stuffing box assembly set forth in claim 16 wherein: said cover includes a hub portion having a bore formed therein for enclosing said at least one spare seal element on said shaft.   
     
     
       19. The stuffing box assembly set forth in claim 16 including: at least one spare fluid slinger ring stored on said shaft in a non-working position and operable to be moved into a working position on said shaft and enclosed within an annular recess formed in said seal retainer.   
     
     
       20. A stuffing box and seal assembly for providing a substantially fluid tight seal at a rotary shaft for a downhole well pump, comprising: a housing including means for connecting said housing to an upper end of a fluid conducting conduit for conducting fluid from a well, said housing including a bore for receiving a rotary shaft extending through said housing and within said conduit, said housing including a first transverse face delimiting a chamber within said housing;   a cover including a transverse end wall and a bore extending therethrough for receiving said rotary shaft, said cover including a second transverse face opposed to said first transverse face and delimiting said chamber, said cover and said housing including cooperating threads formed thereon for connecting said cover to said housing;   a seal holder disposed in said chamber and including a bore for receiving a resilient seal element engageable with said rotary shaft and forming a seal around said shaft to substantially prevent fluid in said conduit from flowing from said conduit to the exterior thereof through said stuffing box assembly, said seal holder including a third transverse face disposed adjacent to said first transverse face;   seal means interposed between said first and third transverse faces and forming a substantially fluid tight seal between said seal holder and said housing to prevent leakage of fluid from said conduit into said chamber;   a spacer member including opposed surfaces thereon engageable with said seal holder and said cover for retaining said seal holder in a working position in said chamber, said spacer member including plural opposed parts operable to be assembled around said rotary shaft when said spacer member is disposed between said cover and said seal holder; and   means engageable with said seal holder for retaining said seal holder against substantial rotation with respect to said housing.   
     
     
       21. The stuffing box assembly set forth in claim 20 wherein: said means for retaining said seal holder against rotation with respect to said housing comprises at least one retaining pin supported on said housing and adapted to project into a slot formed in said seal holder.   
     
     
       22. The stuffing box assembly set forth in claim 20 wherein: said parts of said spacer member include means forming a hub portion when said parts are disposed opposite each other, said hub portion being operable to be disposed in said bore in said seal holder.   
     
     
       23. The stuffing box assembly set forth in claim 22 wherein: said spacer member comprises two substantially identical parts each forming half of a generally cylindrical member comprising said spacer member.   
     
     
       24. The stuffing box assembly set forth in claim 22 wherein: said spacer member includes means forming an annular chamber for storing a spare seal element in a non-working position supported by said shaft.   
     
     
       25. In an apparatus including a rotary shaft extending from a structure within which pressure fluid is to be contained, a stuffing box and seal assembly connected to said structure and operable to form a substantially fluid tight seal at said rotary shaft, said stuffing box and seal assembly including a stuffing box including a housing part and a cover part removably connected to said housing part and adapted to be moved axially away from said housing part along said rotary shaft, a first annular seal element adapted to be supported in said stuffing box to form a fluid tight seal between said first annular seal element and said rotary shaft, a seal retainer adapted to be supported within said stuffing box for retaining said first annular seal element in a working position, and at least a second annular seal element stored in a non-working position on said rotary shaft and operable to be moved into a working position within said stuffing box upon removal of said first annular seal element from said stuffing box without removing said stuffing box from said rotary shaft. 
     
     
       26. The invention set forth in claim 25 wherein: said second annular seal element is stored on said rotary shaft within said stuffing box.   
     
     
       27. The invention set forth in claim 26 wherein: said second annular seal element is stored in a cavity form within said seal retainer.   
     
     
       28. The invention set forth in claim 25 including: a third annular element disposed on said rotary shaft and forming a fluid dam to prevent seal lubricant/coolant from flowing out of said stuffing box, and a fourth annular element disposed on said rotary shaft and operable to be moved along said rotary shaft into a working position in said stuffing box in place of said third element without removing said stuffing box from said rotary shaft.   
     
     
       29. The invention set forth in claim 25 wherein: said rotary shaft includes a hard surface cylindrical sleeve disposed thereon and engageable with said seal elements in at least their working positions, said sleeve including an elongated annular sleeve member including a portion disposed at one end and engaged with an annular head disposed on said shaft, said head including means for forcibly engaging said shaft to position said sleeve member in a predetermined working position on said shaft, said sleeve member being releasably engageable with said head, and a seal element disposed between said sleeve member and said head to prevent leakage of pressure fluid from said structure.